The impact of the use of statins on the prevalence of dementia and the progression of cognitive impairment.

Background: Previous evidence suggests that treatment with 3-hydroxy-3-methylglutaryl-coenzyme-A reductase inhibitors (statins) has a positive impact on dementia. We decided to investigate the association between the use of statins and the prevalence of dementia and statins' impact on the progression of cognitive impairment.
Methods: This is a case-control and a retrospective cohort study of a community-based ambulatory primary care geriatric practice. We included a convenience sample of all patients (N = 655, mean age 78.7 +/- 0.3 years, 85% Caucasian, 74% women) with hypercholesterolemia or dementia, or using statins. We compared those using statins with those who do not with respect to the clinical diagnosis of dementia and its subtypes and the progression of cognitive impairment.
Results: At the initial visit, 35% had dementia, and 17% were using statins. After covariate adjustments, patients on statins were less likely to have dementia (odds ratio [OR] for dementia based on composite definition = 0.23; 95% confidence interval [CI] [0.1-0.56], p =.001, OR Alzheimer's disease = 0.37; 95% CI [0.19-0.74], p =.005, OR vascular dementia = 0.25; 95% CI [0.08-0.85], p =.027). At follow-up, patients on statins showed an improvement on their Mini-Mental Status Examination score by 0.7 +/- 0.4 compared to a decline by 0.5 +/- 0.3 in controls, p =.025 (OR for no change or improvement on statins = 2.81; 95% CI [1.02-8.43], p =.045) and scored higher on the Clock Drawing Test (difference of 1.5 +/- 0.1, p =.036).
Conclusions: The use of statins is associated with a lower prevalence of dementia and has a positive impact on the progression of cognitive impairment.